{"doi":"10.1371/journal.pone.0312819","title":"Development of a rapid antigen-based lateral flow assay for tick-borne spotted fever rickettsioses","abstract":"Tick-borne spotted fever rickettsioses (SFRs) continue to cause severe illness and death in otherwise-healthy individuals due to lack of a timely and reliable diagnostic laboratory test. We recently identified a diagnostic biomarker for SFRs, the putative N-acetylmuramoyl-l-alanine amidase RC0497. Here, we developed a prototype laboratory test that targets RC0497 for diagnosis of SFRs. The concentrations of RC0497 in sera of Rickettsia rickettsii-infected guinea pigs and R. conorii-infected mice were determined by stable isotope dilution-parallel reaction monitoring mass spectrometry (SID-PRM-MS), ranging from 0.1 to 1.1 ng/ml. Using europium chelate nanoparticle reporters, we developed a lateral flow assay (LFA) and evaluated the test with a panel of serum samples of mock and experimentally infected animals. Interestingly, 21 of 22 (95.5%) serum samples from R. rickettsii-infected guinea pigs and R. conorii-infected mice yielded positive results with a ratio of test line / control line greater than the cutoff value determined for non-infected animals. All uninfected samples were in agreement with the intended results, suggesting that the initially assessed specificity of the test is 100%, among these samples. Mice infected with a lethal dose of R. conorii and treated with doxycycline on day 3 post-infection (p.i.), upon RC0497 detection by LFA, displayed significantly decreased rickettsial loads, comparable to the sublethal infection group on day 5 p.i.. A panel of human serum samples spiked with various concentrations of recombinant RC0497 were analyzed by LFA, suggesting that the limit of detection of the LFA was 0.64 ng/mL. These findings suggest that the timely detection of RC0497 by a europium LFA offers guidance for treatment, leading to a significant improvement in infection outcomes. This work, for the first time, shows significant promise for a rapid and easy-to-use platform offering a timely diagnostic assay for severe SFRs.","journal":"PLoS ONE","year":2025,"id":518866,"datarank":0.0,"base_score":0.0,"endowment":0.0,"self_citation_contribution":0.0,"citation_network_contribution":0.0,"self_endowment_contribution":0.0,"citer_contribution":0.0,"corpus_percentile":null,"corpus_rank":null,"citation_count":6,"citer_count":0,"citers_with_citation_signal":0,"citers_with_endowment":0,"datacite_reuse_total":0,"is_dataset":false,"is_dataset_confidence":0.963,"is_data_producer":false,"deposit_databanks":null,"is_oa":true,"file_count":0,"downloads":0,"has_version_chain":false,"published_date":"2025-01-01","fair_score":null,"fair_percentile":null,"algorithm_id":"datarank_citation_only_1hop_v6","ranking_scope":"data_only","authors":[{"id":439570,"name":"Yingxin Zhao","orcid":"0000-0002-8872-5860","position":1,"is_corresponding":false},{"id":1000149,"name":"Kristen Brosamer","orcid":null,"position":2,"is_corresponding":false},{"id":1387204,"name":"Yogita Pal","orcid":null,"position":3,"is_corresponding":false},{"id":378073,"name":"Lucas S. Blanton","orcid":"0000-0002-4653-2323","position":4,"is_corresponding":false},{"id":917801,"name":"Esteban Arroyave","orcid":"0000-0002-4996-1094","position":5,"is_corresponding":false},{"id":1155073,"name":"Carsen Roach","orcid":"0009-0004-2652-2736","position":6,"is_corresponding":false},{"id":439576,"name":"David H. Walker","orcid":"0000-0002-3309-4360","position":7,"is_corresponding":false},{"id":529939,"name":"Katerina Kourentzi","orcid":"0000-0001-5891-6415","position":8,"is_corresponding":false},{"id":439571,"name":"Rong Fang","orcid":"0000-0003-0213-0960","position":9,"is_corresponding":false},{"id":529944,"name":"Richard C. Willson","orcid":"0000-0002-0900-6148","position":0,"is_corresponding":true}],"reference_count":53,"raw_metadata":null,"created_at":"2026-07-19T02:49:14.184995Z","pmid":"39823491","pmcid":null,"fwci":null,"citation_percentile":null,"influential_citations":0,"oa_status":null,"license":null,"views":0,"total_file_size_bytes":0,"version_count":0,"fair_f":null,"fair_a":null,"fair_i":null,"fair_r":null,"fair_zscore":null,"fair_rationale":null,"fair_model":null,"fair_agent_version":null,"fair_fulltext_source":null,"fair_has_llm":null,"fair_computed_at":null,"clinical_trials":[],"software_tools":[],"db_accessions":[],"linked_datasets":[],"topics":[]}